The work in this lab is directed toward an understanding of the relationship between chromosome structure and gene expression. Many of the experiments proposed here take advantage of unique features of meiotic lampbrush chromosomes. These large chromosomes are less condensed than metaphase chromosomes and have visible, highly transcribed loops representing about 5-10% of the genome. In situ hybridization, DNase I sensitivity, immunocytochemistry and fluorescent analog cytochemistry will be used in identifying some of the sequences transcribed on loops and the associated chromatin structures. Using the chicken lampbrush chromosome system, the W (sex) chromosome will be examined for transcription of a repetitious sequence comprising 50% of this chromosome. Other experiments involve constructing a detailed map of a single loop, and from this, sequences forming the loop/chromomere junction will be identified. These loop base sequences will be tested for their function as matrix attachment sites in other cell types and for their position within the organization of the nucleus. Both scanning and transmission electron microscopy will also be used to examine the lampbrush loop organization, especially the loop/chromomere junction in greater detail.